As someone who has considerable field experience with Australian Sapphires I am constantly confounded by the representation of dark opaque blue sapphires as being representative of Australian Sapphires. This is especially apparent in the marketing of many asian gem-houses when in reality the dark opaque stones labelled as "Australian" are often low-grade asian stones. An Aussie miner would throw such stones on the tailings heap. The Australian stones are spread through the market and labelled as they appear ie. if it looks like a kashmir stone they may well market it as such. It is not widely known amongst the public, but Australia has some very high-grade stone that can rival any of the world's deposits.  I spend the majority of my time around Glen Innes and the Kings Plains in  Northern New South Wales and have encountered the entire rainbow of sapphires. There are yellows and cornflower blues that compare to the stones of Ratnapura, Sri Lanka and vivid greens, pinks, reds and a royal blue that is often marketed as a Thai Royal Blue. The stone pictured below closely resembles a Kashmir Blue and comes from a patch I located on the Kings Plains, New South Wales, Australia.

Australian Sapphires located by Author (Top) and genuine Kashmir stones (bottom)  (c)2005

If you are looking for a stone of a particular colour and appearance ask an Australian dealer (many of the sellers on Ebay are the actual miners) to list stones for sale that may appeal to you. After all, the cornflower blue you may eventually buy through a retailer could have originated from these people to begin with. You can cut out the middle man, avoid the possibility of dubious stone treatments and buy high grade stones direct from the Aussie miners.